I do not know when the thought was conceived, but once inside me, it rooted deep and threatened through every hour of the day and night to burst forth, explosively, to rupture my stomach and split apart my lungs and maybe even my very skull, if I would not allow the energy of it to come through me and be played out naturally.

You might call it a disease, this thought, but to me, it was my child; my genius child, dissatisfied with slow umbilical gestation, feasting instead straight from the stem of my brain and gulping down the will and the life and the desire it needed, and I grew, steadily, to love it.

With it inside me, I knew pain, yes, but not a senseless sore-bear toothache to dull the senses. Before my suffering, the world opened and unfolded and filled with colour so vivid it burned my eyes, and then it began to wrinkle, to rot and peel, and beyond I saw the righteous martyr-fires of Heaven and the cold, damp, decaying pits of Hell.

Don’t you dare accuse me of madness. I could show you madness.

The old man was staying in my house as a guest, and it wasn’t that I hated him. He was polite and kind, and had little by way of money or wealth. He smiled a welcome in the morning, and bid me sweet dreams before bed. But there was something in his pale blue eye and the cataract smothering it - milk gone thick, gone stale – that put within me the seed that grew into that, my most precious thought: I would take his life.

In that final week, I was more kind to the old man than I had ever been to anything in my life. He was too kindly himself to be suspicious of my sudden generosity. Each night around midnight, unbeknownst to him, I would creep down the landing, inch open his door just enough to put my head inside, and there I would wait a minute, ten, twenty, for my eyes to adjust to the gloom.He slept like a baby, curled up, the duvet and a whole heap of blankets besides pulled up to his throat, his hair thin and wispy and seeming to glow in the faint light from the street that slipped around the edges of the heavy curtains.

I watched him like this for seven exhaustive nights, but for each, he harboured his sickly ghost of an eye beneath a papery eyelid, and so I became as a ghost myself, and left his room as if I had never been – and in the morning, at the hour I knew he liked to rise, I knocked sharply on his door with a cup of coffee and wished him a good day with such fervence I could not imagine the day would dare defy me.

On the eighth night, I was struck by a superstition and took instead of my usual hour two to cross the landing between our rooms, open his door, and push my head inside. My eyes took longer to adjust, and once they did, I was overcome with hatred, with fear, and with joy – I saw the world close in, burst open, peel back – I felt my lungs snap off from the stems and sink into my stomach, felt my stomach fizz and burn, and in my head my brain grew hot, engorged and expanded with the thought, my most precious thought, swelling with the promise of fruition within it, and I could feel the bone splinter and snap, no longer able to contain it. His eye, his monstrous, evil, ghost, corpse of a stale-milk, cataract, swallowed-up eye, scorning the safety of that thin-skin-veil, was open, and looking right at me!

I knew triumph, and chuckled to myself, and gasped in awe that finally, finally I would see my child born. The old man moved suddenly in his bed, as if startled, and I clapped a hand to my mouth.Silence – or so I assumed. I was consumed by the chittering of my child, by the blood pounding passed my ears as it rushed down, I imagined, to fill me up from my toes. I pushed the door open further, and though I did not hear it, it must have groaned for the old man did, then, rise in the bed, eyes blinking, and call out “Who’s there?”

My fingers, warm against my face, parted, and though I had not meant to, I said aloud, “Nothing, no one, the wind in the chimney,” – my voice became high and strange to my ear – “a mouse, scurrying across the floor, a cricket chirping, a night assailant, a robber at the window” – I laughed, full of myself – “death, come watching!”

He groaned, and still his sick eye stared, and the marrow in my bones chilled and turned to dust, and I could hear a thudding now, low and dull, quickening, irregular, and I knew, as I knew all things then, that this was not the sound of my body, but the old man’s. My senses, reaching outside of myself, had zeroed in on that most private sound, the beating of his heart, and now it drew me on like a drum of war.

I leapt into the room, throwing the door wide, and whipped out the pillow from beneath his head, sending the old man rolling away. He caught himself with another groan that might have been trying to stretch itself into a word but I smothered it, pressing the pillow down onto his face and my foe, squatting there in his eye socket.

Still, his heart beat, fired up with the youth and vigor of an ensign – little drummer boy –, until I lent my whole self against him and, at length, it ceased. The old man was dead.

I sank down beside the corpse, my body thick with pleasure. I felt the thought – your disease full-blown, my child fully-fledged –, fat and heavy with satiation, leave me. Knowing, in that moment, that I had succeeded, that I had kept my promise to this, the wish of my very truest self, I knew a joy greater than anything I had ever known before.

In a haze, I knew that time was passing. Now that my thought had left me, I could feel the world closing back up, the way it had been before my thought was conceived, but I could hear yet the first weak rays of dawn rattle as they hit the roof above me, hear them whisper as they crept around the edge of the curtains. I could smell the spiders, the mice, the dust in the floorboards beneath me. Exhausted, I drifted into dream.

I had no sooner settled into sleep than was rudely shaken from it. There came a knocking. It rapped, insistent, and made my head ache. Then came another, low and dull and quick that rolled beneath the first – my ear recognised it, but in my momentary daze could not place it. I listened, and the first came again, more urgent this time, and some instinct – manners, politeness, social decorum, a true madness, if you’re looking for it – took over and spirited me across the landing, down the stairs, and presently to open the door.

There stood a man and a woman, officers of the law, smartly dressed, hands in their pockets, tiny speakers buzzing with tiny voices against their collar bones, which they ignored. The neighbours had heard a noise and, thinking it unusual from so usually-quiet a neighbour, had called in it and the seed of suspicion, foul play, had been planted.

I invited them in, ignoring the buzzing and the rolling rumble of the yet unplaced thump…thump… beneath, and boiled water for tea. They asked me questions, chatted about the weather, tried, as surreptitiously as they could, to ascertain who else might have been around to make a sound in my otherwise quiet, neat little house.

It was fine to begin with. I was sure I had assuaged their suspicions, calmed their doubts, attributed the sound to a nightmare I had suffered an hour or so before, and promised to make a full apology to my disturbed neighbour at a more respectful hour. But as I had spoken and as they had nodded, and changed the subject, and were making conversation of the weather again, that low dull quick rumbling banging knocking sound increased in volume until my ears were full of it. I clapped my hands to my head in an effort to block it out, but they helped none. The officers looked at me with alarm, their mouths making shapes that looked like they meant concern, but I could not hear a word they spoke. The entirety of my inside self was filled with this sound, this constant, irrepressible beating, like a drum, calling me on to-.

I got up from my chair, still with my hands clamped over my ears, and charged out of the room with the officers on my tail. Up the stairs and across the landing, I knocked open the door to the old man’s chamber with my elbow and saw the body lying there, lifeless, the head turned towards me and that hideous, sickly demon eye staring, unblinkingly, into the centre of my soul.